SQL Mobile 2005 NVarChar Truncation Problem?

I have a field in an .sdf database which is an nvarchar(350).

I'm accessing the database using .Net Compact Framework 2.0 and have setup the SqlCeCommand as follows:

SqlCeCommand command = this.conn.CreateCommand();
command.CommandText = "INSERT INTO Items (FeedID, Title, Link, Description, PublishDate) ";
command.CommandText += "VALUES (@feed, @title, @link, @desc, @date)";

command.Parameters.Add("@feed", SqlDbType.Int);
command.Parameters.Add("@title", SqlDbType.NVarChar, 75);
command.Parameters.Add("@link", SqlDbType.NVarChar, 300);
command.Parameters.Add("@desc", SqlDbType.NVarChar, 350);
command.Parameters.Add("@date", SqlDbType.DateTime);

command.Parameters["@feed"].Value = article.Feed;
command.Parameters["@title"].Value = article.Title;
command.Parameters["@link"].Value = article.Link;
command.Parameters["@desc"].Value = article.Description;
command.Parameters["@date"].Value = article.Published;

command.ExecuteNonQuery();

Now when the command executes, I get the following error message:

InvalidOperationException@desc : String truncation: max=255, len=330,

Given that my NVarChar is actually 350, why on earth is it saying max=255?

Any help would be appreciated.